USRE23367E - Thermally controlled grinder head - Google Patents

Description

May 22, 1951 R. P. GARRISON ET AL ERMALLY CONTROLLED GRINDER HEAD '7 Sheets-Sheet 1 Original Filed Feb. 2. 1938 Twm url

UN TvN y 1951 R. P. GARR'ISON ET AL Re. 23,367

THERMAL-LY CONTROLLED GRINDER HEAD '7 Sheets-Sheet 2 Original Filed Feb. 2

y 1951 R. P. GARRISON ET AL Re. 23,367

THERMALLY CONTROLLED GRINDER HEAD Original Filed Feb. 2, 1958 7 Shee'ts-Sheet 5 May 22, 1951 R. P. GARRISON ET AL Re. 23

THERMALLY CONTROLLED GRINDER HEAD '7 Sheets-Sheet 4 Original Filed Feb. 2, 1938 y 1951 R. P. GARRlSQN ET AL Re. 23,367

THERMAL-LY CONTROLLED GRINDER HEAD 7 SheetsSheet 5 Original Filed Feb. 2, 1938 dmmm,

May 22, 1951 R. P. GARRISON ET AL THERMALLY CONTROLLED GRINDER HEAD 7 Sheets-Sheet 6 Ori inal Filed Feb. 2, 1938 '7 Sheets-Sheet 7 Filed Feb. 2, 1938 Original keissued May 22, 195i 23,367 THEBMALLY CONTROLLED GRINDER HEAD Ralph P. Garrison and John R. Garrison, Dayton, Ohio, assignors to Garrison Machine Works,

Inc., Dayton,

Original No; 2,271,637

Serial No. 188,358;

Ohio, a corporation of Ohio dated February 3, 1942,

February 2, 1938. Application for reissue November is, 1943, Serial Nb.

28 Claims. (01. 511-165) Matter enclosed in heavy brackets I: appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates" the additions made by reissue.

This invention comprises amethocl and apparatus for controlling stresses, strains and variations of position in machine tools and machine tool parts developed incident to temperature fluctuations and resultant contraction and expansion as produced by operation of the machine tool and changes in atmospheric temperatures. The invention is particularly applicable to any machine tool wherein work pieces and tools are relatively positioned and the work piece and tool relatively moved for affecting a desired result in the work piece, although it is equally applicable to machines and apparatus of all kinds.

It might seem that the natural and logical manner of counteracting the effect of heat generated during operation of the machine would be by air cooling the part, or by circulating other cooling medium by which the generated heat would be dissipated. However, cooling of the bearing and frame merely causes contraction and tightness of the bearing with a consequent development of more heat, necessitating an increased amount of cooling. Use ing principle is likewise conducive to undesirable sweating. The present system overcomes these difiiculties and provides for uniform operating conditions by heating the bearing, frame, and the spindle, and other parts in contact directly or indirectly with the bearing and frame, to a degree at least equal to the highest temperature likely to be developed during operation, :and providing automatic control means for maintaining thisas a uniform working temper- :ature by circulation of heating medium andthe employment of suitable heaters therefor under thermostatic control.

In machines as ordinarily constructed, bearings are fitted at a temperature far belowthat which is attained during the operation of the machine, and are likewise set up in their supportsat the same low temperature with the re- :sultthatthe supports and bearings both attain :a considerably higher temperature during opera- :tion of the machine over a period of time than w n t ea in s werefitted. As a result of this assembly practice, when the machine is put into operation there is a definite change in position in the machine and parts due to expansion and contraction, which is directly proportional to change in temperature, and which directly affects machine alignment and the work result producedbyfihe machine. In accordance with this invention, vital parts of a machine are manuiactured and. assembled and the bearings therefor fitted .or

run in while the various mae adaptable for of the cool--' uarly adapted to centering and holding beveled gears for performing machining, refinishing, boring, or grinding operations thereon. Itisujnderst'ood, however, that the present device is holding article s other than scars and for all manner of machining, grinding, boring and other operations. As well as embody. ing means for controlling the temperature of the machine, the machine is so constructed and arranged that work may be supported without overhang, and with the center of the work piece practically in line with the front work support end. Also, it is so constructed and arranged that the work maybe loaded into the chuck from a lateral direction between the supporting bearings, and means are provided for protecting an operator fr'om contact with moving parts.

One object of the invention is to'simplify the construction aswell as the means and mode of operation of a device as disclosed herein whereby such devices maynot only be economically manufactured, but will be more eficient and accurate in use,,,adaptable to a wide variety of work pieces, of relatively few parts and unlikely to get out i of repair.

method and apparatus for temperature control; which will eliminate any delay incident to a machine being successively in and out of a desired operating condition.

A further object of the invention is to increase the life of bearings and the journals operating therein by providing for a closer original fit between the bearings and journals, and maintaining such fit substantially constant so far as it may be affected by contraction and expansion.

A further object of the invention is to provide for maintenance of the same clearance between bearings and associated journals, except such variations as may be induced by wear, at all times and regardless of whether the machine tool is in or out of operation.

A further object of the invention is to provide for maintenance of the lubricant at a constant temperature and thus eliminate any rise in temperature on initial operation of the machine tool due to the lubricant being at a relatively high viscosity and rubbing over itself.

A further object of the invention is to provide for maintenance of a temperature in the machine which is higher than room temperature wherebytemperature of the machine is not affected by fluctuations in room temperature.

A further object of the invention is to provide, by temperature control, for the elimination of endwise float of spindles due to expansion and contraction of the spindle, bearings, frame and other parts.

A further object of the invention is to insure uniformity of precision method production by maintaining the operating condition constant.

A further object of the invention is to provide a-machine of the character hereinafter described whereinthere is a minimum or no overhang of the work piece With respect to its support.

A further object of the invention is to provide for ease of loading a Work piece in its support.

A further object of the invention is to provide safety features in the machine for the protection of the operator of the tool from moving parts.

A further object of the invention is to provide a machine possessing the meritorious characteristics above mentioned.

With the above primary and other incidental objects in view, as will more fully appear in the specification, the invention consists of the features and methods of construction, the parts and combinations thereof, and the mode of operation, or their equivalents, as hereinafter described and set forth in the claims.

Referring to the accompanying drawings wherein is found the preferred but obviously not necessarily the only form of embodiment of the invention,

Fig. 1 is a view, partly in elevation and partly in section, showing a Work holder or chuck having temperature control means applied thereto in accordance with the idea disclosed by this invention.

Fig. 2 is a top plan View of the work holder or chuck shown in Fig. 1.

Fig. 3 is an end elevation of the work holder or chuck shown in Figs. 1 and 2, and showing more fully the temperature control means.

Fig. 4 is a front elevation showing the regulating and indicating mechanism for the temperature control means.

Fig. 5 is a rear elevation of the regulating and indicating mechanism shown in Fig. 4.

Fig. 6 is a top plan view of an entire machine tool, including the work holder or chuck, the tool for operating on the work, and the holding means therefor.

4 Fig. 7 is an elevation of a modified form of the invention showing the heating principle and the apparatus therefor as applied to the base of the machine.

Fig. 8 is an elevation showing another modified form of the invention with the heating principle and apparatus therefor applied to the base of V the machine.

Fig. 9 is a perspective view showing the door which permits access to the hollow spindle, such door being in open position.

Like parts are indicated by similar characters of reference throughout the several views.

For illustrative purposes, but with no intent to unduly limit the application or scope of the invention, the assembly herein shown and described is especially designed for grinding the rear, side and bore of a typical automotive driving gear of the spiral bevel type.

Referring to the drawings, and particularly Fig. 1 thereof, there is shown a work holder or chuck including a base portion l for upright supporting members 2 and 3 in which suitable bearings 4 and 5 are respectively mounted, and in which bearings a spindle 6 rotates. The upright 2 is provided with a bearing cover plate 7 and a thrust ring 8, the thrust ring being held in position by bolts 9. Both the front and rear bearings have adjusting nuts Ill, and the upright 3 is shown as having a bearing liner H, with the spindle B mounted to float in the bearing 5.

The portion of the spindle 6 extending forwardly of the upright 3 and bearing 5 is hollow to form a holder in which the gear or other work piece is mounted. The hollow portion of the spindle ii has a lateral opening permitting access to the interior of the spindle, and a door 6a, Fig. 9, having a suitable latch is hinged to the spindle and rotates therewith covering the opening in the spindle side walls and barring access to the interior of the spindle when closed. Such door also serves to properly balance the spindle. An interchangeable chuck l2 in the forward end of the interior of the hollow spindle 6 is secured to the spindle by bolts l3 and includes locating studs l t, the interchangeable chuck being fully disclosed in the copending application of John Russell Garrison, [Serial No. 302,385, filed November 1, 1939] Serial No. 42,101, filed September 25, 1935, and issued April 11, 1939, as U. 8. Patent No. 2,153,829. Inorder that a work piece inserted into the hollow spindle 6 may be guided into proper position relatively to the chuck I2, a loading tube I5 is disposed within the hollow spindle and in advance of the chuck i2, the loading tube being inclined in a direction toward the chuck so as to guide the work piece into proper engagement therewith.

Within the hollow spindle 6, and to the rear of the chuck l2 and loading tube I5, is a support for a pinion gear shaft which takes the form of an L-shaped member l6 having one leg secured to the inner surface of the hollow spindle 6 as by bolts l1 and having the shaft supporting leg l8 extending toward the center of the hollow spindle G. The leg I8 terminates in such position that the free end of the gear shaft may be readily engaged by a center bar l9 having a replaceable center 20 in its forward end and movable longitudinally or endwise in bushings 2| within the small end of the spindle 6 under the action of a compression spring 22 bearing against a collar 23 rigidly secured to the center bar for yieldingly engaging the free end of a gear shaft and yieldingly forcing the gear into engagement with the interchangeable chuck I2. The leg I8 may be made adjustable as to height if desired.

The spindle E is rotated in its bearings 4 and 5 to rotate the gear relative to a tool supported at the end of the spindle by an overrunning clutch including driving rollers 26 and a pulley 21 over which a belt from a motor or the like passes, or by means of a hand wheel 28 rigidly mounted on the spindle .3 by bolts 39. The spring 22 is held in place by a cover casting 29 and screws 29a. To stop rotation of the spindle 6, a brake band 3| surrounds the drum of hand wheel 28 and is operable by a hand lever 32, Fig. 2, pivotally mounted on the frame I and interconnected with one end of the brake band 3|.

A hand lever 33, Fig. 2, moves the center bar I9, Fig. 1, longitudinally or endwise in its bushings 2| against the resistance of the compression spring 22. The hand lever 33 is rigidly secured to one end of a shaft 34 extending transversely of the base I beneath the spindle 6, and the shaft 34 has rigidly secured to its opposite end a pinion 35 which coacts with a rack 36, Fig. 5, forming a part of arack bar 3! on the rearward side of the base I and mounted in suitable supports 38 for endwise or longitudinal movement. Rigidly secured to one free end of the rack bar 31 is a forked arm 39, the forked end of which loosely engages a collar 49 secured to the center bar i9. Thus, when the hand lever 33 is moved to the left, Figs. 4 and 5, to rotate the shaft 34, the rack bar 31 is moved longitudinally or endwise by the pinion 35 and rack 36 and moves the center bar I9 longitudinally or endwise against the resistance of the compression spring 22 through the connection between the rack bar and the center bar I9 by means of the forked arm 39 and collar 49. To vary the extent of movement of the center bar I9 so as to accommodate gear shafts of different lengths, the collar 40 may be adjusted along the length of the bar.

Referring to Figs. 1 and 2, the chuck I2 is within the vertical plane of the front spindle bearing 4. Thus, there is no overhanging of the gear with respect to the bearing support for the chuck which lends to freedom from chatter and insures a minimum of run-out error as compared to chucks where there is a substantial overhang of the chucked gear. Where overhang is present, any error in the work head bearings or in mounting the interchangeable chuck is multiplied, and this error might very well be so great as to make it impossible to achieve the extreme accuracy and fine finish required.

Lubrication is provided for the bearings i and 5 by an oil pump 4! operated by a projection 32 on the spindle 6, which on each rotation strikes the pump piston rod 41 and actuates the pump piston. Lubricant is forced from the pump 4! into an oil filter 48, Fig. 4, from which it flows without pressure other than the few inches the head of oil in the filter is above the bearings through inlet conduits 49 and to the front and rear bearings 4 and 5. respectively. Pump 4| delivers more lubricant than is needed to the filter 43, and the overflow returns to the supply tank by way of a pipe 48a and an overflow header. Thus a constant head of lubricant is maintained in the filter 48.

The inlet conduits 49 and 50 lead to passages 5| and 52 in the bearing supports 2 and 3, and communicate with pass ges 54 and 55 in the bearings 4 and 5 which convey the lubricant to eccentrically formed oil grooves in the bearings 4 and 5,

Such bearings 4; and 5 utilize all the lubricant line is obviated.

they require, and excess lubricant not used by the bearings 4 and 5 leaves the Sight glasses through conduits 58 and 59 (Fig. 3) to bearing overflow header 63. Used and surplus oil passing through the bearings 4 and 5 (Fig. 1) leave the bearings through channels 51, 51a and 56,, 56a, which are connected to a suitable reserve oil tank. The header 60 is considerably larger than the combined capacity of the overflow conduits leading into it. Consequently, there is never any back pressure in the header to restrict the flow of lubricant. Sight glasses are disposed in the lubricant conveying lines, and means are provided for venting the lines. A hand or .auto-. matic valve may be provided in the overflow line 48a from the filter 48 to the header B0 to break the syphonic action when the device is not in use so as to prevent the lubricant in the filter from siphoning out into the header.

The center bar I9 is hollow to receive a supply of lubricant introduced under pressure through fitting 2d at the end of the bar, the lubricant entering a chamber 5i between the bushings 2| by way of a port 62. The chamber EI holds a supply of lubricant which is conveyed to the bearing surfaces of the center bar I9 and bushings 2| by the longitudinal or endwise movement of the center bar.

The uprights 2 and 3 include jackets t3 and; G4 which surround the bearings 4 and 5 and the spindle 6 at its points" of rest in the bearings for the circulation of a liquid, for example, water. Heaters I01 and i92, one for each bearing, preferably electric, are disposed in the bottom of each jacket, and a flow circuit is provided through each jacket 63 and 64, by means of pipes S5, 66 and 6? having liquid supply reser- VOlIS 63 interconnected therewith. Thus,

thermo-syphonic circulating system is estabwith the cooled or cold liquid enteringlished, at the bottom of the heated rises in the jackets to thus establish a flow. The liquid reservoirs 55 maintain the flow circuit including the jackets and the pipes 65,. 66 and 6! constantly filled, and likewise serve as a deterrent on rapid or violent temperature fluctuation of the liquid in the circulating system. As the liquid becomes heated it rises into the reservoirs 6B and displaces a corresponding vclume which is at atmospheric temperature, the displaced liquid flowing into the line, and by reason of this constant interchange of liquid any rapid change in temperature of the liquid in the It will be noted that the top positions of the jackets 3 and s4 have greater exposed areas than the bottoms of the jackets. Consequently, heat will be dissipated faster at the tops of the jackets, whereby the temperature of the liquid will be approximately equal throughout the entire jackets. Thermostatic control means 69, one for each of the front and rear bearings, are provided for controlling operation of the heating units and thus the temperature of the liquid in the jackets. Suitable air vents prevent air pockets forming in the jackets.

Heat from the liquid in. the jackets 5.3 and 64 is dissipated to the bearings d and 5 and associated parts of the machine and by controlling the temperature of the liquid, the temperatureof the machine parts may be regulated. That is, the highest temperature attained bythe machine parts as a result of machine operation maybe adopted as norma for the temperature of the; i id n h jack ts, nd hat mp ture i the jackets where it is sub jected to the heating means, and upon being":

machine maintained constant both during machine operation and when the machine is idle.

Such normal temperature, while higher than room temperatures, is always less than the tem- ':-perature at which the oil film in the bearings l scribed makes it possible to make and set the bearings and bearing fits with the machine parts at running temperature, or whatever tempera-- ture has been adopted as normal. That is, in effect the machine as concerns the frame, the bearings and spindle assembly may be assembled at a temperature which does not change thereafter whereby the fit between the bearings and spindle and the bearings and their supports will remain the same without any change due to expansion or contraction resulting from temperature change. Thus, there may be a very minimum of clearance between the spindle and bearings, with that clearance remaining uniform through control of the temperature of the parts, which makes possible the use of a very thin oil, is being known that thin oil has less tendency to rub over itself and produce friction and heat.

It will be noted that the oil passages 52, '54 and 55 through which oil is introduced to the front and rear bearings 4 and 5 are entirely surrounded by metal in intimate contact with the heated liquid in the jackets 53 and 5d. The oil flow to the bearings is sufficiently slow that the oil is heated while flowing through the passages to the bearings and reaches the bearings at the same temperature as the heating liquid or the machine at that point. It is possible that the front and rear bearings may be intentionally maintained at different temperatures, but the oil temperature at each bearing is automatically controlled, and the heating of the oil is more positive since it is done substantially at the point of use and is not affected by outside conditions during transit to the bearings. This method of heating the oil is less expensive than external heaters which would also be less positive.

For convenience, an instrument panel may be mounted in conjunction with the machine to support the oil filter 48, the thermostats 69, and the sight glasses in the oil lines. The heaters IOI and I92 are preferably connected with small pilot lights II which serve to indicate that the heaters are or are not operating, and which may also be mounted upon the instrument panel 10. There is a pilot light for each heater. erators light 12 may be provided on the instrument panel for the operators convenience.

In Figs. '7 and 8 the heating principle is applied to the base of the machine which supports both the Work holder and the tool holding carriage, to thereby provide a machine base which will be stable and will not change position by contraction and expansion due to variations in temperature caused by any means and thus affect the relative positions of the work piece and tool. As shown in Fig. '7, a work holder as hereinbefore described is mounted on a sub-base or table I3 which is, in turn, mounted on a floor base I4. The sub-base or table I3 is shown as being a cored, ribbed, box-like member forming a tank for containing liquid, and having therein immersion heaters. 15, preferably electric, but which may be of any well-known type. One or a plurality of thermostat bulbs, disposed in either the liquid in the tank formed by the table or subbase 13 or in the metal going to make up the table or sub-base as the installation may require,

may be provided to cooperate with suitable thermostatic control means for regulating operation of the immersion heaters I5. Thus, the subbase or table may be maintained at a constant temperature and thereby unaffected as to position by temperature change and resultant contraction and expansion. Heat dissipated to the base I4, to the work holder hereinbefore described which is mounted on the table or subbase I3, and to the tool holder Ti, will serve likewise to maintain these parts at a constant temperature and eliminate changes in position due to expansion or contraction. A liquid sup ply reservoir 78 is provided to supply liquid to the tank formed in the sub-base or table 13 as required to maintain a constant head of liquid in the tank. It will be understood that all parts may be fit together or assembled while at the temperature to be maintained constant after fitting or assembly thereby eliminating stresses and strains resulting from subsequent temperature changes.

In Fig. 8 is illustrated another application of the heating principle. Whereas in Fig. '7, the means for heating the table or sub-base I3 and the heating means for the work holder mounted thereon are separate, in the structure shown in Fig. 8 the heating means is common to both. The sub-base or table forms a tank for containing liquid and in which there are immersion heaters I5. A conduit "I9 leads from the interior of the tank, preferably at one end, to a pump operated by a motor 8i so that liquid heated in the tank may be drawn therefrom by'the pump and forced through a conduit 82 to branch conduits 83 and leading to the respective jackets G3 and 64 about the bearings 4 and 5. The liquid is drawn out of the jackets 63 and 6G by the pump through conduits 85 and 86 and through a common conduit 81 to and through the tank in the sub-base or table I3 and over the immersionheaters 15 for reheating and recirculation through the jackets 63 and 64. Suitable thermostatic control means are provided for regulating operation of the immersion heaters I5 and a water supply reservoir 88 maintains the flow circuit continually filled with liquid.

For alternative use when desired, a pump 89 operated by a motor 89a may be provided which draws liquid from the tank in the sub-base or table I3 past a single immersion heater 90 in a tank 90a through conduits 9i and 92 and forces it through conduits 93, 83 and 84, through the respective jackets 63 and B4, and through conduits 8 5, 86 and 81 back to the tank in the sub-- base or table 13. The immersion heaters 15may or may not be utilized as heating means, and athermostatic control means including a bulb 94' is provided in conjunction with the immersion heater 96 for controlling operation thereof. Con-- tinuous pumping of a relatively large volume of liquid will result in the temperature of the liquid returning to the tank I3 being practically the same as the temperature of the liquid at the outlet of the tank or at the point of entry into the jackets 63 and 64.

It is important that the centers in the part being finished have a smooth surface and be of the correct angle to insure the part rotating properly and being finished correctly when supported between male centers on the machine upon which the work is being done. One method of griding centers has been to move the grinding element straightinto the work and then feed the wheel laterally across the work until spark ing indicated that the center had been ground concentric and round. On completing the grinding operation, some concentric lines or circles are visible on the ground surface, having been left there by the grinding Wheel. For the purpose of eliminating such concentric lines or circles, the tool holder ll, Fig. I, which is mounted for movement of the tool spindle 95 both parallel and perpendicularly to the center line of the work holder and work piece is also mounted for movement diagonally to the center line of the work holder and work piece. As shown in Fig. 8, the hand wheel 96 is provided for moving the tool holder 11 and tool 9'! into the work piece along a line parallel to the longitudinal center line of the Work piece. The hand wheel 88, Fig. 6, is provided for moving the tool holder 71 and tool 91 perpendicularly to the work piece center line, both movements of the tool holder 71 being along suitable ways as is Well known in the art. To move the tool holder 1? and tool 91 diagonally of the longitudinal center line of the work piece, a hand wheel I03, Fig. 6, is provided for actuating a pinion gear 99 which meshes with a rack I disposed diagonally to the center line of the Work holder and work piece, suitable Ways being provided for movement of the tool holder and tool in such direction. The temperature control means hereinbefore described serves to eliminate any change in position of both the work piece and tool due to expansion and contraction of parts induced by temperature change.

Controlling the relationship of the various machine units or parts to each other, and maintain-v ing a given setting or adjustment of the machine units or parts constant regardless of temperature changes exteriorly of the machine by controlling temperature change Within the machine insures uniform accuracy of work produced in the machine and saves much machine operating time now lost in making part contraction and expansion compensating adjustments in machines not temperature controlled.

The principle herein disclosed is applicable to any and all machines where accuracy of work produced is dependent upon the relative position of a part of the machine or its fixtures to some other parts or fixtures, and where such relative position is susceptible to variation due'to temperature change from any cause and resultant contraction or expansion of the parts or fixtures.

From the above description it will be apparent that there is thus provided a device of the character described possessing the particular features of advantage before enumerated as desirable, but which obviously is susceptible of modification in its form, proportions, detail construction and arrangements of parts without departing from the principle involved or sacrificing any of its advantages.

While in order to comply with the statute, the invention has been described in language more or less specific as to structural features, it is to be understood that the invention is not limited to the specific features shown, but that the means and construction herein disclosed comprise the preferred form of several modes of putting the invention into efiect, and the invention is therefore claimed in any of its forms or modifications within the legitimate and valid scope of the appended claims.

Having thus described our invention, claim:

[1. In a machine of the character described wherein heat is developed incident to machine operation, a heating means for minimizing temperature produced fluctuations in expansion and contraction of a machine part and resulting deviation of operating and work members by subjecting the machine part to heat produced independently of that developed by machine operation, and a regulator for controlling the independently produced heat so as to subject the machine part to a degree of heat inversely proportionate to that produced by machine operation and thereby maintain 'a substantially uniform temperature of the machine part at a degree at least equal to the highest degree produced by machine operation] [2. In a machine of the character described wherein heat is developed incident to machine operation, and the temperature of the machine parts fluctuates in accordance with the degree of machine operation and atmospheric influences and conditions, a thermo-syphonic operating heating means effective to absorb the temperature fluctuations and maintain the temperature of the machine uniform to minimize temperature produced expansion and contraction of the machine parts and resulting deviation of operating and work members, a regulator for controlling operation of the thermo-spyhonic: operating heating means, and means associated with the thermo-syphonic operating heating means effective to deter rapid or violent fluctuations therein] 3. The method of minimizing [constructional] contractional and expansional change and part displacement in a machine, the machine being subjected to [wherein] fluctuating degrees of heat [are] developed incident to machine operation with coincident contractional and expansional change in the relative positions and dimensions of the machine parts, which includes supplying heat to the machine parts other than .that developed by machine operation and in degrees converse to the degrees of heat developed by machine operation whereby to maintain a uniform temperature of the machine parts.

4. In the art of manufacture and part assembly of a machine wherein temperature fluctuations are produced by machine operation, the method which consists in heating the parts to a temperature at least equal to the highest temperature produced by machine operation, and finishing and assembling the parts while at that temperature.

5. In a machine including a rotatable member and bearings therefor, and wherein rotation of the member relative to the bearings produces a rise in the temperature of the member and bearings, a fluid thermo-syphonic operating supplemental heating means for minimizing temperature produced expansion and contraction of the member and bearings and resulting deviation of the member and bearings by maintaining the temperature of the member and bearings substantiall equal to the highest temperature produced by rotation of the member relative to the bearings, a regulator for the supplemental heat-- ing means and means for maintaining the supply of heating fluid constant.

6. Ina machine assembly of the character described, a frame, spaced bearings therein, a rotatable hollow spindle supported in the bearings, a work supporting and locating member within the spindle, a lateral opening in the spindle through which access may be had to the Work supporting and locating means, and means for minimizing expansion and contraction of the member and bearings and resulting deviation of heat generated by and during operation of the machine or any parts to compensate for fluctuations in such generated heat and maintain the machine and its operating parts at a uniform temperature.

"7. In a machine assembly of the character de scribed, a frame, spaced bearing therein, a rotatable hollow spindle supported in the bearings, a work supporting and locating means within the spindle, a lateral opening in the spindle through which access may be had to the work supporting and locating means, a cover for the opening, and means for minimizing expansion and contraction thereof and resulting deviation of operating and work members including means for supplying heat to the assembly supplemental to heat generated by and during operation of the machine or any parts and inversely proportionate thereto to compensate for fluctuations in such generated heat andmaintain the machine and its operating parts at uniform temperature.

8. In a machine assembly of the character described, a frame, spaced bearings therein, a rotatable hollow spindle supported in the bearings, a work supporting and locating means within the spindle, a lateral opening in the spindle through which access may be had to the work supporting and locating means, means for minimizing expansion and contraction thereof and resulting deviation of operating and work members including a fluid thermo-syphonic operating means for minimizing expansion and contraction thereof and resulting deviation of operating and work members including means for supplying heat to the assembly supplemental to heat generated by and during operation of the machine and inversely proportionate thereto to compensate for fluctuations in such generated heat and maintain the machine and its operating parts at a uniform temperature, and means for controlling the amount and degree of heat supplied.

[9. In a machine wherein heat is developed incident to machine operation, supplemental heating means for minimizing expansion and contraction of the machine parts and resulting deviation of the operating and work members by controlling temperature fluctuations and resultant contractional and expansional displacement of machine parts, and means associated with the supplemental heating means effective to deter rapid or violent fluctuations in temperature thereof] 10. The herein described method of minimizing deviation of operating and work members incident to expansion and contraction of the parts of a machine tool, including the step of subjecting the machine to supplemental heat supply inversely proportionate to the temperature fluctuations of the machine produced incident to its operation and influence of atmospheric conditions, and maintaining [the procedure being such 6 that] the temperature of the machine [is maintained] substantially constant at a degree at least equal to the highest temperature induced under ordinary working conditions.

ll. The method of producing a machine tool having parts moving relatively to each other during machine operation and thereby generating heat and producing an increase in machine temperature, which includes assembling the parts into operative relation while at a temperafi rfl substantially coincident with the temperature produced in the parts by machine operation, and thereafter supplying supplemental heat to the tool to compensate for fluctuations in such generated heat and maintain the machine and its operating parts at a constant temperature at least equal to the temperature of the, machine parts at assembly.

12. The method of operating a machine where in relatively movable parts are [so arranged with respect to each other as to produce'friction and generate] subjected to friction generated heat by their relative movement, which includes subjecting the parts to heat from a fluid medium [and] independently of the heat generated by friction between the relatively movable parts, and of a higher degree than that generated by friction be tween the relatively movable parts, to maintain the parts at a temperature higher than that induced by such friciton.

13. The method of minimizing contractional and expansional part displacement and change of dimension in a machine, the machine being subjected to [wherein] fluctuating degrees of heat [are] developed incident to machine operation'with coincident contractional and expan sional change in the relative positions and dimen sions of the machine parts, which includes con stantly circulating a fluid heating medium in effective relation with the machine parts and regulating the temperature of the circulated fluid heating medium so as to supply a degree of heat which, either supplemented by or independently of the heat developed by machine operation, maintains the machine parts at a preselected temperature.

14. The method of minimizing contractionaland expansional part displacement and change of dimension in a machine, the machine being subjected to [wherein] fluctuating degrees of heat [are] developed incident to machine" operation with coincident contractional and expan sional change in the relative positions and di-' mensions of the machine parts, which includes supplying supplemental heat to the machine parts, and regulating the supplied supplemental heat with respect to the degree of heat developed by machine operation in such manner as to maintain the machine parts at a preselected temperature at least equal to the maximum temperature developed by machine operation.

In a machine assembly wherein tool and work members are moved relatively to each other for prescribed operation on the work member by the tool, a frame, hearings in the frame, a rotatable spindle supported in the bearings, a work supporting and locating means associated with the spindle, and means for minimizing tempera ture 'produced contraction and expansion of the assembly parts and resulting deviation of tool and work members from prescribed position, in cluding means for supplying heat to the assembly supplemental to heat generated by and during machine operation and inversely proportionate thereto to compensate for fluctuations in such generated heat and maintain the machine assembly at a uniform temperature, and a regulator for controlling the amount and degree of supple.- mental heat supplied.

16. In a machine assembly wherein tool and work members are moved relatively to each other for prescribed operation on the work member by the tool, a frame, bearings in the frame, a rotatable spindle supported in the bearings, a

15 work supporting and. locating means associated with the spindle, and means for minimizing temperature produced contraction and. expansion of the assembly parts and resulting deviation of tool and work members from prescribed position. including a fluid thermo-syphonic operating means for supplying" heat to the assembly supplementa] to heat generated by and during machine operation and inversely proportionate thereto to compensate for fluctuations in such generated heat and maintain the machine assembly at a uniform temperature, and a regulator for controlling the amount and degree of supplemental. heat supplied.

17. In a machine, in combination, a tool member, a work holdingmember, one of said members being rotatable relative to the other of said members, metallic means for supporting said rotatable member, a heating element for communicating heat to said supporting means, said heating element being operable independently of movement of either of said members and independently of the lubrication system of said machine, and thermostatic means responsive to the temperature of the metal of said supporting means for controlling the operativeness of said heating element.

18. In a lathe, in combination, a headstock, means supported by said headstock for rotatably supporting a piece of work to be operated upon, a tool adapted to operate upon said piece of work, an electric heatelr element located adjacent to the bottom of said headstock, said heating element being operable independently of movement of either of said members and independently of the lubrication system of said machine, and a thermostat positioned to be responsive to the temperature of the metal of said headstock, said heater element being responsive to said thermostat.

19. In a machine, in combination, cooperating members, one of which is rotatable relative to the other of said cooperating members, means for communicating heat to the {region of said r0- tatable member, said heat communicating means including a heating element and an electrically operated pump for delivering heat exchange med um from the region of said heating element to the region of said rotatable member, said heating element and said pump being operable independently of movement of either of said members and independently of the lubrication system of said machine, and thermostatic means responsive to temperature conditions in the region of said rotatable member for controlling the operativeness of said heating element.

20. A machine assembly of the character described including a frame, spaced bearings therein, a revoluble hollow spindle supported in said bearings, work supporting and locating means within the spindle, a lateral opening in the spindle through which access may be had for insertion and removal of a work piece relative to the spindle, a chamber in said frame contiguous to the bearing for circulation of heat eachange medium, source of supply of heated medium! for circul tion through said chamber, means for inducin "circulation thereof, and thermal responsive means for fluctuating the temperature of theheat exchange medium in accordance with the degree of heat produced by operation of the revoluble spindle.

21. A machine tool, including relatively movable parts, wherein ununiform heated areas are developed in the machine, and wherein differential heating of such areas is compensated by supplying additional heat to the machine proportioned inversely to the fluctuating degree of temperature of the machine parts, characterized by a machine frame, a heater device mounted on the machine frame, thermostatic control means for the heater device also mounted on the machine frame and subjected to the fluctuating temperature influence of the machine parts automatically regulating the heater device inversely to the degree of temperature of the machine parts to supply a fluctuating degree of supplemental heat to the machine sufficient to maintain substantially constant temperature level thereof at least as high as the maximum degree of its acquired temperature.

22. A machine having relatively moving operating parts, wherein the relative movement of such parts induces unequally distributed rise of temperature throughout the machine with resultant change of operatin conditions, including a thermal compensating system therefor comprising circulatory passages embodied in the machine frame contiguous to the bearings of the relatively moving palrts for circulation of heat exchange medium through said passages, means for inducing circulation of said medium, a heater member incorporated in the machine increasing the temperature of the circulating heat exchange medium inversely to the temperature influence thereon of the operation generated heat, and an automatic regulator for the heater member, the oonstruction and arrangement being such that fluctuations of temperature of the machine parts are minimized by supplying thereto a supplemental fluctuating degree of heat ample conjointlywith otherwise acquired heat thereof to maintain the machine temperature substantially uniform.

23. In a machine including a rotatable member and bearings therefore, wherein rotation of the member relative to the bearings pr oduces a rise in the temperature of the member and bearings thereby subjecting the machine parts to resulting unequal expansion and contraction incident thereto, supplemental heating means for minimizing temperature produced expansion and contract-ton of the machine parts and resulting deviation of the member and bearings by maintaining the temperature of the machine parts substantially equal to the highest temperature produced by rotation of the member relative to the bearings, and a regulator for the supplemental heating means responsive to the conjoint efiect of the heat generated by machine operation and the supplemental heating means.

24. The herein described method of maintaining uniform dimensions of a machine under varytemperature conditions wherein the elements thereof are sub'ject to deflection by expansion and contraction of the machine incident to fluctuations of temperature influence thereon, including providing a heat exchange medium in intimate relation with the machine, heating the heat ea:- change medium and inversely proportioning. the transmitted warmth afiorded by the heat exchange medium to the thermal condition to which the machine is subjected, the method of procedure and steps being such that the machine is maintained at a substantially constant temperature level equal to or higher than the maximum temperature influence to which it may be subjected.

25. The herein described method of maintaining dimensional stability in a machine including subjecting the machine to thermal conditioning influence at a predetermined higher temperature level than the maximum temperature to which it is normally subjected by use and automatically maintaining said predetermined machine temperature to maintain in said machine a substantially balanced condition of expansive and contractive influence at the prescribed dimension thereof.

26. A temperature exchange system including a bearing and a moving member operative therein by which operation generated heat is developed within the bearing, and means for compensating for varying thermal conditions and minimizing expansion and contraction of the parts, a chamber for heat exchange medium contiguous tothe bearing wherein heat exchange medium may absorb operation generated heat from the bearing, a thermostatic regulator subiect to the influence of the heat exchange medium, and a heater for the heat exchange medium controlled by the thermostatic regulator for supplying a varying supplemental degree of heat to the heat exchange medium inversely to the degree of operation generated heat supplied thereto, the construction and arrangement being such that the combined operation generated heat and the supplemental heat supplied by said thermostatically controlled heater will maintain the temperature of the heat exchange medium and the structural parts of the mechanism subject to the influence thereof at a substantially uniform temperature level higher than the maximum operation generated heat developed in said bearing.

27. An apparatus including a rotatable member and a bearing therefor, wherein rotation of the member relative to the bearing produces a rise of temperature of the member and bearing, wherein fluctuations of the resulting temperature are automatically compensated to minimize variations of expansion and contraction of said member and bearing, a fluid pressure operated supplemental heating means for minimizing temperature produced expansion and contraction of the rotating member and bearing and resulting deviation thereof by maintaining the temperature of the member and bearing substantially equal to the highest temperature produced by rotation of the member relative to the bearing, a regulator for the supplemental heating means, and means for maintaining the supply of heating fluid under pressure substantially constant.

28. In a machine of the character described,

16 relatively moving parts wherein a fluctuating de gree of heat is developed incident to machine operation, such operation developed heat producing fluctuations in expansion and contraction of said parts, heating means subjecting the machine parts to heat produced independently of that developed by machine operation, and a regulator responsive to the temperature of the machine parts for controlling the degree of independently produced heat so as to subject the machine parts to a degree of heat inversely proportionate to that produced in said relatively moving parts during machine operation and thereby maintain a substantially uniform temperature of the machine parts at a degree at least equal to the highest degree of heat produced in said parts by machine operation to minimize heat produced fluctuations in expansion and contraction of the parts and resulting deviation thereof.

RALPH P. GARRISON.

JOHN R. GARRISON.

REFERENCES CITED The following references are of record in the file of this patent: I

UNITED STATES PATENT Number Name Date 691,104 Blodgett Jan. 14, 1902 1,312,285 Stevens Aug. 5, 1919 1,332,970 Burres Mar. 9, 1920 1,404,538 Mitchell Jan. 24, 1922 1,409,736 Lea Mar. 14, 1922 1,715,750 Gena. June 4, 1929 1,726,572 Koepsell Sept. 3, 1929 1,806,422 Bell et a1 May 19, 1931 1,811,383 Brown June 23, 1931 1,825,627 Bowen Sept. 29, 1931 1,904,429 Evans Apr. 18, 1933 r 2,009,823 Van Vulpen et a1. July 30, 1935 2,045,790 Midyette June 30, 1936 2,055,651 Burrell Sept. 29, 1936 2,070,811 Sassen Feb. 16, 1937 2,071,033 Hanna, Feb. 16, 1937 2,150,749 Price Mar. 14, 1939 2,166,940 Conradson July 25, 1939 2,232,537 Kollsman Feb. 18, 1941 FOREIGN PATENTS Number Country Date France May 7, 1932.

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